Techniques are described for the exchange of control signals between a controlled unmanned aircraft (i.e. drone) and a ground control station and for the transmission of communication signals, such as video, from the drone to the ground control station so that the signals are more difficult to intercept or jam. The video signal transmitted from the drone can be an analog RF signal employing one or more of video scrambling, RF signal inversion, hopping, usage of a wide frequency range and other techniques. To secure the control signals between the drone and the ground control station, techniques can include hopping, encryption and use of a wide frequency range.

A data transmission method, a base station, and user equipment are presented. The method includes performing rotation processing on a preset precoding matrix; performing precoding processing on to-be-sent information according to a precoding matrix obtained after the rotation processing; and sending to-be-sent information obtained after the precoding processing. In the embodiments of the present disclosure, indication information shared by a transmit end and a receive end is used to indicate whether to rotate a precoding matrix, and to-be-sent information is precoded according to the indication information. The transmit end and the receive end in this method learn the indication information in advance, and system security is improved by instructing the precoding matrix to perform flexible transformation.

Secure channel training to enhance the confidentiality level of a power domain non-orthogonal multiple access (NOMA) communication system when impaired by eavesdropping attacks coming from inside and outside of the network. In a first scenario, a cooperative jammer available in the system defines an external source of entropy that is independent of the channel variation rate. While the jammer provides secrecy inside the network, the proposed invention is configured to secure the network from outside, encoding the system information, which is exchanged during the training phase, using only the channel state. In a second scenario, the cooperative jammer is not available; with the secrecy inside and outside of the network ensured through a different parameterization. That parameterization is done in a way that the required system information is encoded using not only the channels, but also a random phase defined in the data communication phase.

The method includes a first encryption step of encrypting each of a plurality of data streams to obtain a respective encrypted data stream, a mapping step of mapping the plurality of encrypted data streams obtained in the first encryption step to a plurality of transmission streams for transmission via the optical transmission units, wherein the transmission streams and optical transmission units are in a one-to-one relationship, and wherein each transmission stream is mapped to by at least two of the plurality of encrypted data streams. The method further includes a second encryption step of encrypting each of the plurality of transmission streams to obtain a respective encrypted transmission stream, and a transmission step of transmitting each of the plurality of encrypted transmission streams obtained in the second encryption step via a respective optical transmission unit.

A transmitter device comprises a transmission antenna with at least one transducer and one signal generation unit for generating an acoustic communication signal to be transmitted to a receiver device including hidden information, wherein the signal generation unit is configured to previously record an original acoustic signal, the signal generation unit capable of generating the communication signal to be transmitted by adding, to an initial signal x(t) derived from the original signal, an auxiliary signal previously multiplied by at least one symbol, the symbol having a phase and/or an amplitude carrying the hidden information and the auxiliary signal calculated from the initial signal by a chosen transformation operator which depends on a steganographic key.

Systems, devices, methods, and instructions for transmitting a signal by an electronic apparatus that include generating transmission data and pseudo-random data corresponding to the transmission data, setting a first pseudo time delay interval for the transmission data and a second pseudo time delay interval for the pseudo-random data, acquiring a data signal for transmitting the transmission data to correspond to the first pseudo time delay interval and a pseudo-random signal for transmitting the pseudo-random data to correspond to the second pseudo time delay interval, and transmitting an overlapping signal including the data signal and the pseudo-random signal.

Disclosed is a secure scheme that incorporates both internal and external eavesdroppers to secure all users' links in the downlink PD-NOMA. In particular, the proposed scheme implies that the BS induces a phase shift in each user's symbol based on its corresponding instantaneous channel phase. The phase shift of each user is restricted such that the original symbol is moved to the location of another symbol in the constellation diagram. Therefore, as each user is aware of its instantaneous channel phase only, it will be able to recover the actual phase of its corresponding symbol. Thus, the proposed scheme does not only protect the data against eavesdroppers, but it also guarantees confidentiality and privacy against all other users.